Which is not secondary sex characteristic

Secondary sex characteristics are the features that become visible at the time of puberty in men and women and at sexual maturity in other animals, like underarm hair or public hair.  

Explanation:

In males, the secondary sex characteristics comprise growth of facial hair and Adams Apple and in females, they are enlarged breasts and widened hips. A disease called Turner syndrome is where a person lacks secondary sex characteristics. In this condition, the females are born with missing or incomplete sex chromosome.

Females suffering from this syndrome are short heighted, exhibit learning disabilities and their puberty is delayed. In lions, development of manes, But they can also be considered non-secondary sex characteristics as these features are visible in both women and men at the time of puberty.

some stis can be transmitted through a handshake. - false